The present invention relates to an electrostatic capacitance type pickup stylus slidably movable on an information storage medium or disc for detecting signals recorded in the form of minute pits along spiral or circular tracks on the disc.
Information storage mediums or discs such as video discs contain signals in the form of minute pits recorded along spiral or circular tracks at a high density. The signals can be picked up by an electrostatic capacitance type pickup stylus which is slidably movable on the disc to detect changes in electrostatic capacitance which are dependent on the recorded signals. The pickup stylus has its end tapered to an extremely small diameter as the track pitch on the disc is small and the wavelengths of the recorded signals are quite short. While the disc is being played, the tapered end of the pickup stylus is held in frictional engagement with the disc which rotates at a high speed. Accordingly, the pickup stylus of the electrostatic capacitance type tends to be worn relatively rapidly.
Various attempts have heretofore been made to fabricate electrostatic capacitance type pickup styli which have a longer service life so that they need to be replaced less frequently. Such pickup styli are generally made of naturally occurring diamond or artificial diamond which is cut and ground to desired contour. Presently available diamond pickup styli are however disadvantageous in that they have ground faces which are relatively poor in grindability and a sliding face having an irregular wear-resistant property, and their longevities vary from stylus to stylus. Fabrication of such diamond pickup styli is costly as it requires a time-consuming and complex grinding process.